We’ve have been seeing the behaviour of Sun and Moon since our birth in this world. Qur’an refers to these natural piece as light (noor) for the moon and lamp (siraaj) for the sun. Also Qur’an states as below,
“Did you see how Allah created seven heavens, one above the other, and made in them the moon a light and the sun a lamp?” Qur’an, 78:12-13
This verse stated thousands of years ago clearly mentions that Moon is a dormant body that reflects light, and Sun is a heavenly body is at a state of combustion that generates both light and heat
Quran And Science
Despite all these hindrance true way to understand Islam is to investigate every situation correlating with Islamic standards & reliable sources.